Linear slot burner



D. H. DESTY LINEAR SLOT BURNER June 30, 1970 5 Sheets-Sheet 1 Filed June 6, 1968 INVENTOR.

DENIS HENRY DESTY BY MORGAN, FINNEGAN, DURHAM 8 PINE ATTORNEYS June 30, 1970 DESTY 3,517,887

LINEAR SLOT BURNER Filed June 6, 1968 3 Sheets-Sheet 23 27 INVENTOR DENIS HENRY DESTY BY MORGAN, FINNEGAN, DURHAM 8 PINE ATTORNEYS June 30, 1970 I D. H. DEsTY 3,517,887

LINEAR SLOT BURNER Filed June 6. 1968 3 Sheets-Sheet 5 INVENTOR.

DENIS HENRY DESTY BY MORGAN, FINNEGAN, DURHAM a PINE ATTORNEYS United States Patent U.S. Cl. 239-568 6 Claims ABSTRACT OF THE DISCLOSURE A burner for fluid, preferably gaseous, fuels comprises one or more elongated fuel ducts each with an elongated fuel exit slit.

The ducts may be corrugated so that their juxtaposition forms air tubes. 7

The exit slit may be packed to increase its exit resistance.

This invention relates to a burner for fluid fuel, i.e. to a burner suitable for use with both liquid and gaseous fuels.

According to the invention a burner for fluid, pref erably gaseous, fuels comprises one or more fuel ducts each of which has an elongated configuration with a longitudinal exit slit positioned so as to direct fuel into a combustion zone, different portions of the fuel ducting being arranged in juxtaposition with one another so as to form air channels adapted to convey air into the combustion zone.

Where only one fuel duct is utilised it must follow a tortuous path through the combustion [Z0116 so that different sections of the duct come into juxtaposition with one another so as to form the air channels. In order to achieve this the fuel duct may follow a serpentine or spiral path.

Where a plurality of ducts are utilised they may be connected in series. This may be achieved by connecting different segments via link passages which are situated outside the combustion zone. This may give configurations similar to the single duct embodiments described in the previous paragraph except that the link passages have no exit slit since they are situated outside the combustion zone.

The preferred arrangement utilises a plurality of fuel ducts connected in parallel, said ducts being aligned side by side so as to form air channels between them.

According to a further feature of the invention, which is preferably incorporated in all the embodiments described above, the fuel ducts have a corrugated configuration and they are aligned so that adjacent ducts contact one another at the extremities of their corrugations so as to form air tubes adapted to convey air into the combustion zone.

Thus a burner for fluid, preferably gaseous, fuels which incorporates the preferred embodiments specified above comprises a plurality of corrugated, elongated fuel ducts which are connected in parallel and each of which has a longitudinal slit which extends over the whole length of the duct adjacent to the combustion zone, the fuel ducts being arranged side by side so that adjacent ducts contact one another at the extremities of their corrugations so as to form air tubes adapted to convey air into the combustion zone.

The invention also includes burners as described above in which the exit slit contains packing to increase the exit resistance. The packing conveniently takes the form of several layers of strip material, e.g. metal gauze or crimped metal foil. As an alternative to the packing,

or as well as the packing, one or both sides of the slit may be crimped. Where there is no packing this crimping helps to increase the resistance and it also helps to define the slit width.

The terms crimped and corrugated have similar meanings in that both imply a wavy configuration but crimped implies a shorter wave length and smaller amplitude than corrugated.

Several embodiments of the invention will now be described by way of example with reference to the accompanying drawings, FIGS. 1-8. In these drawings:

FIG. 1 shows a typical vertical cross-section through a burner according to the invention when corrugated fuel ducts are not employed,

FIGS. 2-5 are different plan views which can be associated with the cross-section shown in FIG. 1,

d FIG. 6 shows the construction of a corrugated fuel uct,

FIG. 7 is a diagrammatic perspective view of a burner using the duct of FIG. 6, and

FIG. 8 is a cross-section showing a packed exit slit.

A characteristic cross-section of a burner according to the invention is shown in FIG. 1. This comprises a plurality of fuel ducts 10 (which may be portions of the same fuel duct as will appear from FIGS. 2, 3 and 4 or sections of different ducts as will appear from FIG. 5) which are arranged in juxtaposition so as to form a plurality of air channels 11.

Each duct 10 is provided along its upper edge with and exit slit 12 which, in the use of the burner, conveys fuel into the combustion zone which is situated immediately above the burner. Natural draught draws combustion air through the air channels.

In order to encourage uniform distribution of fuel it is necessary that the internal resistance of the fuel ducts 10, i.e. the resistance to longitudinal flow of gas, shall be sufliciently less than the resistance of the exit slit 12, i.e. the resistance to the flow of gas from the interior of the duct to the combustion zone, so that there is substantially uniform pressure along the fuel duct 10. The exterior of the fuel ducts 10 is arranged so that the air channels 11 have a suitable shape for directing combustion air into the combustion space.

FIG. 2 shows how the cross-section of FIG. 1 can be achieved by a single fuel duct formed into a serpentine configuration. This duct has a single slit 12 which extends over its whole length and is connected to the fuel supply via a header 14 which has no exit slit since it is outside the combustion zone. A similar result can be achieved,

by the use of a spiral configuration as shown in FIG. 3.

The arrangement shown in FIG. 4 comprises six separate fuel ducts 10 connected in series by means of link passages 13. Since these, like the header 14, are situated outside the combustion zone they have no gas exit slits. Each of the fuel ducts 10 is provided with a single exit slit 12 which extends across the whole width of the combustion zone.

The arrangement shown in FIG. 5 utilises six separate fuel ducts 10 which are connected in parallel, each via its own header 14, to a common supply pipe 21. The six fuel ducts are arranged side by side to provide five air channels 11. Each fuel duct is provided with a single exit slit 12 which extends across the width of the combustion zone.

FIG. 6 shows the formation of a corrugated fuel duct from a strip of corrugated metal. The strip has a shoulder 15 at the top so that a top rim 16 is formed; a similar shoulder 17 at the bottom forms a bottom rim 18 on the same side as the top rim 16- The fuel duct is formed by folding the strip so that the corrugations match up and soldering the two portions of the bottom rim 18 to make a gastight joint. This produces a high resistance slit from the two halves of the upper rim 16. FIG. 6 shows the folding almost completed. If desired one or both of the shoulders 15 and 17 maybe crimped. This helps to increase the resistance and to define the slit width.

The burner shown in FIG. 7 was formed from four ducts of the type illustrated in FIG. 6. These ducts are aligned so that adjacent ducts contact one another at the extremities of their corrugations so as to form air tubes 20. Enough contacts are soldered to give stability to the structure.

At their open ends the ducts are connected to a supply pipe 21 so that, in the use of the burner, fuel gas passes through the interior of the ducts and emerges into the.

combustion zone via the slits 22. The draught of combustion draws air through the air tubes 20.

A fuel duct with packing in the exit slit is conveniently manufactured from a rectangular strip of metal. The length of the strip is equal to the length of the fuel duct (measured round the corrugations) and the width of the strip is equal to twice the height of the fuel duct.

As the first stage of manufacture the strip is folded along the centre line and, as shown in FIG. 8, this produces a U-shaped cross-section having arms 23 and 24, and packing 25 consisting of several layers of metal gauze or crimped metal foil, is inserted into the mouth 'of the U.

In the final stage of manufacture the U is corrugated, either by rolling or pressing, and this compresses the packing to ensure a high exit resistance.

Several of these fuel ducts can be placed side by side to form a burner similar to that shown in FIG. 7.

I claim:

1. A burner for fluid fuels which comprises one fuel duct which has an elongated configuration with a longitudinal fuel exit slit positioned so as to direct fuel into a combustion zone, the fuel duct having a corrugated 4- configuration and following a tortuous path so that different sections thereof are arranged in juxtaposition with one another, the sections in juxtaposition being aligned so that they contact one another at the extremities of their corrugations so as to form air tubes adapted to convey air into the combustion zone.

2. A burner according to claim 1 in' which the duct follows a serpentine path.

3. A burner according to claim 1 in which the fuel duct follows a spiral path. I

4. A burner according to claim 1 which comprises packing situated in the exit slit to increase the exit resistance.

5. A burner for fluid fuels which comprises a plurality of fuel ducts each of which has an elongated configuration with a longitudinal fuel exit slit positioned so as to direct fuel into a combustion zone, the fuel ducts having a corrugated configuration and being connected in parallel and aligned side by side so that adjacent ducts contact one another at the extremities of their corrugations so as to form air tubes adapted to convey air into the combustion zone.

6. A burner according to claim 5 which comprises packing situated in all the exit slits to increase the exit resistance.

References Cited UNITED STATES PATENTS 1,267,448 5/ 19181 Piatt 239-568 X 2,525,350 10/1950 Hanson 239--556 X 2,615,509 10/1952 Whittington 239 568 X 3,035,633 5/1962 Palko 239-568 X FOREIGN PATENTS 170,655 3/1960 Sweden.

M. HENSON WOOD, 111., Primary Examiner M. Y. MAR, Assistant Examiner 532 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,5l7 887 Dated June 30, 1970 Inventor(s) Denis Henry Desty It; is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 2, line 30, for "and" read -an--;

Col. 2, line 33," for "channels." read --channels ll.--.

SIGNED AND QEALEU (SEAL) Attest:

EdwaniM- Flmbmlrwmms E. sum, .m.

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